-51.16% is the change from 645 to 315
Calculation steps:
[( 315 - 645 ) ÷ 645] x 100 = -51.16%
Formula
Percentage change = [(315 - 645) / 645] x 100
Subtract the new number by the original number
315 - 645 = -330
-330 ÷ 645 = -0.5116279069767442
-0.5116279069767442 x 100 = -51.16%